The technical scope of the present invention is that of electro-hydraulic generating sets or rotating actuating gear used to rotate the turrets or cupolas, for example of weapon systems.
To date, hydraulic motorisations to drive turrets or cupolas in rotation are known. Such actuating gear have been frequently used in dated equipment or weapon systems and notably in vehicles that had a hydraulic generating set on board, already installed for other functions, for example propulsion. In these cases, the actuating gear amounted to no more than a hydraulic motor, the hydraulic power being supplied by the equipment's central hydraulic generating set.
The current trend is to gradually replace hydraulic generating systems by electric generating systems to supply equipment and notably vehicles. This naturally leads to the use of motorisations to drive the turrets or cupolas, of a type adapted to the power available on the equipment, in other words back-geared motors. These systems are classically built around an electric motor. The mechanical characteristics of such a motor are generally not enough in terms of torque and are oversized in terms of speed. Thus, its output is coupled with reducing gear. This reducing gear is classically a gear-based mechanical system well known to the expert. Such a back-geared electric motor is currently used in the area of driving turrets and cupolas that are installed on either fixed equipment or vehicles.
Such a back-geared electric motor is able to provide substantial power at a sustained rate if it there is an electric supply of sufficient capacity available. The back-geared electric motor has the secondary advantage of being very compact because of the small number of components and the use of compact gears of the planetary gear train, worm wheel or flexible external crown type. A large speed reducing ratio allows, in addition, the necessary volume of the motor to be reduced.
However, the profile of use of a turret or cupola motorisation is very intermittent. The cupola or cupolas remain inactive or on stand-by for long periods and are then individually used periodically but intensively. Furthermore, in the event that several cupolas are used, they are rarely used at the same time but rather sequentially. On typical example of use is, further to a long period of inactivity, to have to carry out a rallying movement of the weapon system. A rallying movement consists in departing from the current or starting position of the system and moving it as quickly as possible to its new position of use. For this, the motorisation must allow a rotation of up to 180° of the cupola head of the weapon system. This rotation must be carried out at faster and faster speeds so as to match the constant evolution of the threats. The cupola then becomes inactive and another may be used to take over.
The profile of power consumed is very intermittent with a low demand on average but punctuated by peaks. The back-geared electric motor is not well adapted to such profiles of demand for power.
Hydraulic power, because of its storage possibilities, for example oil-hydraulic, is able to accommodate great fluctuation in the demand for power. However, in spite of its great specific output allowing a substantial power supply, the relatively large number of necessary components discourages the expert when he has to design a compact architecture compatible with the limited space in the equipment.